Gray and white hair yellows naturally with age or with the use of yellow-colored shampoos, hair sprays and the like. Accordingly, the art recognizes that Ext. D & C Violet No. 2 can be used in shampoos, rinses, conditioners and the like to neutralize this yellow cast on gray and white hair by replacing the yellow color with small, tinctorially effective amounts of Ext. D & C Violet No. 2 to permit the hair to return to its natural color. One such product is Clairol's Shimmer Lights shampoo containing water, sodium lauryl sulfate, lauramide DEA, amodimethicone, hydrolyzed animal protein, lauryl alcohol, tallowtrimoniumchloride, glycol stearate, citric acid, fragrance, monoxynol-10, methyl and propyl parabens, imidazolidinyl urea, disodium EDTA, External D & C Violet No. 2, D & C Violet No. 2, and other ingredients at a pH of 6.08. Another example of a similar commercially available Ext. D & C Violet No. 2 containing conditioner is Silver Fox shampoo for gray hair manufactured by Morningside Laboratories. This product includes water, ammonium lauryl sulfate, lauramide DEA, glycol stearate, hydrolyzed animal protein, tetrasodium EDTA, hydroxypropyl methylcelulose, imidazolidinyl urea, methyl paraben, propylparaben, fragrance, and Ext. D & C Violet No. 2. One of the problems with these and other commercial compositions for removing the yellow cast on gray or white hair by substituting Ext. D & C Violet No. 2 for the yellow cast is that the Ext. D & C Violet No. 2 dye does not have much affinity for human hair and much of the dye from the compositions is wasted after scalp contact and rinsing. Because much of the Ext. D & C Violet No. 2 dye is never attached to the hair, much of it flows over the scalp of the user where the dye has a greater affinity for the scale than for the hair resulting in scalp staining. That portion of the Ext. D & C Violet No. 2 that does remain with the hair is loosely bound and easily washes away from the hair within one or two washings.
Consequently, no existing product provides a composition capable of tinctorially effective Ext. D & C Violet No. 2 color change on gray or white hair without simultaneous skin or scalp staining. In accordance with the present invention, it has been found that dialkyl quaternary ammonium compounds having two alkyl radicals predominantly in the C.sub.12 to C.sub.18 range dramatically and unexpectedly provide tinctorially effective deposition of External D & C Violet No. 2 dye onto human hair to reduce or eliminate yellowing of hair without the prior art problem of skin or scalp staining.
Long chain monoalkyl quaternary ammonium compounds and hydrogenated tallow-derived quaternary salts have been used in cream rinse products as hair detangling agents where the long alkyl chains are derived from coconut oil or tallow fat (predominantly C.sub.12 to C.sub.18). The monoalkyl quaternary ammonium surfactants penetrate into wet hair, and interact with hair structural bonds to relax the wet hair fiber while, at the same time, providing a lubricating film to the hair surface that contributes to the ease of wet combing--see An Introduction to Quaternary Ammonium Compounds, Cosmetics & Toiletries, Vol. 94, Nov. 1979, pp. 33-41. The long chain monoalkyl quaternary ammonium compounds also are known in cream rinses and the like to have an effect of binding fatty alcohols and esters, perfume oils and other waxy and oily constituents to the hair surface and to improve the hair texture by softening it and eliminating static flyaway.
One of the common mono fatty alkyl quaternary ammonium compounds used in hair conditioning products is cetyl trimethyl ammonium chloride (CETAC) having a Cosmetic, Toiletry and Fragrance Association (CTFA) name cetrimonium chloride. Another long chain alkyl quaternary ammonium compound commonly used in hair conditioning products is stearyl dimethyl benzyl ammonium chloride (SDBAC), CTFA name stearalkonium chloride. These long chain monoalkyl quaternary ammonium compounds are used in hair conditioning products at concentrations ranging from tenths of a percent to two percent by weight, since higher concentrations of these materials can produce a higher risk of ocular damage and skin irritation.
In accordance with the present invention, it has been found that particular fatty dialkyl quaternary ammonium compounds in an amount of 0.5 to 2.5 weight percent of a composition containing Ext. D & C Violet No. 2 dye unexpectedly provide a composition capable of substantially reducing or eliminating yellowing of human hair and wool without visible skin staining.